Abrasive tools expandable in size have been widely used to size and surface finish holes during a machining operation in which an abrasive insert of a tool is inserted into the hole and rotated and reciprocated therein to machine the hole.
For machining holes of relatively large diameter such as a diameter greater than one (1) inch, prior art abrasive tools have employed multiple abrasive elements spaced about the circumference of the tool, a single abrasive member with a circumferentially spaced carbide shoe, and an abrasive sleeve or helical element. Such tools are disclosed in U.S. Pat. Nos. 1,841,343; 1,874,856; 1,903,343, 1,910,658; 1,960,555; 4,173,852 and 4,199,903.
A particular expandable honing tool having an abrasive stone element and one or more bearing shoes spaced circumferentially around the tool body is illustrated in U.S. Pat. No. 2,815,615. The bearing shoes are provided to maintain constant pressure between the abrasive element and the wall of the hole being honed. The bearing shoes are made of a relatively soft metal such as a zinc alloy which wears so as not to mar the surface of the hole being honed and must be periodically replaced. The bearing shoes thus are removably attached to the tool.
For honing holes of relatively small diameter, such as diameter less than one (1) inch, the lack of space in the hole to be honed has required honing tools having simple construction and a small number of components, including a limited number of abrasive elements on the tool. For example, U.S. Pat. No. 2,787,097 illustrates a honing tool for machining relatively small diameter holes wherein the tool includes a single abrasive stone element and a pair of elongated shoes spaced 120.degree. apart around the tool circumference to provide a three point contact with the surface of the hole being honed. The shoes are removably attached to the tool so that replacement thereof is possible to compensate for wear.